[ILUG] More memory problems [& booting large disks]

[Rob]

David Ryan wrote:

> I asked a question a few days ago about a problem where my machine
> reports 128m, but Linux (SuSE 6.1) only recognises 64m.  Quite a lot
> of people mailed me back suggesting adding mem=128 or mem=120 to
> the boot parameters.
>
> When I try anything like this my machine boots for a bit, but hangs just
> after Linux tells me how many bogomips my machine does.  If I stick
> memory=128 or memory=128m or memory=120, or even memory=48 the
> machine boots just fine but still reports 64m.  Any other switches anyone
> could suggest ?
>
> Cheers,
>
> David

emm......I don't have to do that anymore (with RH 6 and 96Mb ram)
but anyway, i got caught with this a few times before.....

from  http://mailer.wiwi.uni-marburg.de/linux/LDP/HOWTO/Hardware-HOWTO-5.html

<hhh>
All memory like DRAM, EDO and SDRAM can be used with Linux. There is one thing

you have to look at: normally the kernel is not supporting
more than 64 Mb of memory. When you add more than 64 Mb of memory you have to
add the following line to your LILO configuration file.

   append="mem=<number of Mb>M"

So, when you have 96 Mb of memory this should become

   append="mem=96M"

Don't type a number higher than the number Mb you really have. This can
present unpredictable crashes.
</hhh>

Also found this re the recent discussion on large hard-drives and LILO>
from
http://www.ssc.com/mirrors/LDP/HOWTO/mini/LILO-6.html

<hhh>



6. Accessing Huge Disks When the BIOS Can't

The system in my office has a 1GB IDE drive. The BIOS can only see the first
504 MB of the IDE. (Where MB means 2**10 bytes, not 10**6
bytes.) So I have MS-DOS on a 350 MB partition /dev/hda1 and my Linux root on
a 120 MB partition /dev/hda2.

MS-DOS was unable to install itself correctly when the drive was fresh. Novell

DOS 7 had the same problem. Luckily for me, "Options by IBM"
forgot to put the "OnTrack" diskette in the box with the drive. The drive was
supposed to come with a product called "OnTrack Disk Manager." If
you only have MSDOS, I guess you have to use it.

So I made a partition table with Linux' fdisk. MSDOS-6.2 refused to install
itself in /dev/hda1. It said something like ``this release of MS-DOS
is for new installations. Your computer already has MS-DOS so you need to get
an upgrade release from your dealer.'' Actually, the disk was
brand new.

What a crock! So I ran Linux' fdisk again and deleted partition 1 from the
table. This satisfied MS-DOS 6.2 which proceeded to create the exact
same partition 1 I had just deleted and installed itself. MS-DOS 6.2 wrote its

Master Boot Record on the drive, but it couldn't boot.

Luckily I had a Slackware kernel on floppy (made by the Slackware installation

program "setup"), so I booted Linux and wrote Lilo over
MS-DOS' broken MBR. This works. Here is the /etc/lilo.conf file I used:

boot = /dev/hda
map = /lilo-map
delay = 100
ramdisk = 0             # Turns off ramdisk in Slackware kernel
timeout = 100
prompt
disk = /dev/hda         # BIOS only sees first 500 MB.
   bios = 0x80          # specifies the first IDE.
   sectors = 63         # get the numbers from your drive's docs.
   heads = 16
   cylinders = 2100
image = /vmlinuz
  append = "hd=2100,16,63"
  root = /dev/hda2
  label = linux
  read-only
  vga = extended
other = /dev/hda1
  label = msdos
  table = /dev/hda
  loader = /boot/chain.b

After I installed these systems, I verified that the partition containing the
zImage, boot.b, map, chain.b, and message files can use an msdos file
system, as long as it is not "stackered" or "doublespaced." So I could have
made the DOS partition on /dev/hda1 500 MB.

I have also learned that "OnTrack" would have written a partition table
starting a few dozen bytes into the drive, instead of at the beginning, and it

is possible to hack the Linux IDE driver to work around this problem. But
installing would have been impossible with the precompiled Slackware
kernel. Eventually, IBM sent me an "OnTrack" diskette. I called OnTrack's
technical support. They told me Linux is broken because Linux
doesn't use BIOS. I gave their diskette away.



</hhh>

rob